Esterified copolymers of polyalkenes/unsaturated acidic reagents useful as lubricant and fuel additives

ABSTRACT

Esterified polyalkene/UAR copolymer reaction products useful as (1) a friction modifier for lubricating oils such as automatic transmission fluids to improve torque capacity and anti-shudder durability and for continuous variable transmissions (CVTs), (2) a friction modifier for fuels or (3) a cold flow improver for diesel fuels are provided. The esterified copolymer reaction product may be used as is or can be further derivatized (e.g., by post treatment of the esterified copolymer reaction product with, for example, ethylene carbonate or boric acid).

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention generally relates to esterified copolymers ofpolyalkenes and unsaturated acidic reagents (“UAR”) and their use aslubricant and fuel additives. More particularly, the present inventionis directed to reaction products derived from polyols and copolymers ofpolyalkenes, e.g., polyisobutenes (“PIB”), and unsaturated acidicreagents, a process for making same and the use of the reaction productas (1) a friction modifier for lubricating oils such as automatictransmission fluids to improve torque capacity, viscosity control andanti-shudder durability and for continuously variable transmissions(CVTs), (2) a friction modifier for fuels and (3) a cold flow improverfor diesel fuels. The esterified polyalkene/UAR copolymer reactionproducts may be used as is or can be further derivatized (e.g., by posttreatment of the reaction product with, for example, boric acid).

2. Description of Related Art

Esterified polyisobutenyl succinic anhydrides have been used asadditives for lubricating oils, e.g., commercially available succinatepentaerythritol esters such as Lubrizol 936 available from The LubrizolCorporation (Wickliffe, Ohio). These esters have been generally preparedby reacting polybutylene and maleic anhydride under suitable conditionsto form a polybutene/maleic anhydride monomer (PIBSA) and then furtherreacting the monomer with pentaerythritol to provide an esterifiedpolybutene/maleic anhydride monomer.

In addition, copolymers of polyisobutene and maleic anhydride have alsobeen prepared. These copolymers are sometimes referred to as“polyPIBSA”. They can be prepared by copolymerizing a polybutenecontaining a high concentration of the methylvinylidene isomer (alongwith other polybutene isomers) with an unsaturated acidic reagent suchas maleic anhydride using a free radical initiator. See, e.g., U.S. Pat.Nos. 5,112,507 and 5,616,668.

U.S. Pat. No. 6,451,920 discloses a process for preparing apolyPIBSA/acid-catalyzed thermal PIBSA monomer mixture employing thesteps of (a) copolymerizing (1) polybutene containing alkylvinylideneisomer and non-alkylvinylidene isomers and (2) an unsaturated acidicreagent under polymerization conditions in the presence of a freeradical initiator; and (b) reacting the product of step (a) with anunsaturated acidic reagent at elevated temperature in the presence of astrong acid. These polyPIBSA/acid-catalyzed thermal PIBSA monomermixtures contain a high ratio of anhydride units per polybutene unit asevidenced by a succinic ratio greater than one (as shown in the '920patent examples). This high succinic ratio is related to multipleanhydride units per polybutene within the thermal PIBSA monomer, and tothe presence of poly-anhydride resin. The mixture can be further reactedwith an amine to form a polysuccinimide or with a polyol to form apolyester. When reacting the polyPIBSA/acid-catalyzed thermal PIBSAmonomer mixture with a polyol, crosslinking between the polyPIBSA,acid-catalyzed thermal PIBSA and resin results.

SUMMARY OF THE INVENTION

The present invention provides esterified polyalkene/unsaturated acidicreagent copolymer reaction products. The present invention preferablyprovides reaction products of polyols with PIB/UAR copolymers (ThePIB/UAR copolymer). Accordingly, in one embodiment of the presentinvention, one or more esterified polyalkene/UAR copolymers is provided,the esterified polyalkene/UAR copolymers comprising a reaction productof a polyol and a copolymer of the general formula (I):

wherein X and X′ in each repeating unit of the copolymer areindependently selected from the group consisting of —OH; —O—R₃ whereinR₃ is a lower alkyl of 1 to 6 carbon atoms; or taken together are —O— toform a succinic anhydride group; n is a whole integer from 1 to 3; R₁ isa lower alkyl of 1 to 6 carbon atoms; R₂ is a polyalkyl group havingabout 9 to about 200 carbon atoms; m is a whole integer of from 1 to 3;x is a number greater than 1 up to 20; Int. is at least one initiatingradical; and Ter. is at least one terminating group; and wherein thecopolymer has a succinic ratio of about 1.

The succinic ratio of the copolymer refers to the ratio of the number ofgroups derived from the unsaturated acidic reagent (m) to the number ofgroups derived from the polyalkene (n), that is m/n.

A preferred embodiment of the present invention is one or moreesterified PIB/UAR copolymers wherein the esterified copolymer is areaction product of a polyol and a copolymer of the formula (II):

wherein n is a whole integer from 1 to 3; R₁ is a lower alkyl of 1 to 6carbon atoms; R₂ is a polyisobutyl group having about 9 to about 200carbon atoms; m is a whole integer of from 1 to 3; x is a number greaterthan 1 up to 20; Int. is at least one initiating radical; and Ter. is atleast one terminating group; and wherein the copolymer has a succinicratio of about 1. The esterified PIB/UAR copolymers may have an averagedegree of polymerization of about 1.1 to about 20. The esterifiedPIB/UAR copolymers may have a number average molecular weight of about600 to about 30,000.

A more preferred embodiment of the present invention is one or moreesterified PIB/UAR copolymers obtained from the reaction ofpolyisobutene with maleic anhydride, in the presence of a free radicalinitiator, followed by partial esterification with a polyol. A mostpreferred embodiment of the present invention is one or more esterifiedcopolymers obtained from the reaction of polyisobutene having a numberaverage molecular weight (M_(n)) ranging from about 350 to about 700with maleic anhydride, in the presence of a free radical initiator,followed by partial esterification with a polyol.

Another embodiment of the present invention is a process for preparingesterified polyalkene/UAR copolymers comprising the step of reacting apolyol with a copolymer consisting essentially of a reaction productobtained from the copolymerization of one or more polyalkenes havingfrom about 9 to about 200 carbon atoms with one or more unsaturatedacidic reagents in the presence of one or more free radical initiators.

Yet another embodiment of the present invention is a process for makingone or more esterified polyalkene/UAR copolymers comprising the steps of(a) reacting a first amount of a polyalkene having from about 9 to about200 carbon atoms with a first amount of an unsaturated acidic reagent inthe presence of a first amount of a free radical initiator to form afirst liquid polyalkene/UAR copolymer, (b) reacting a second amount ofpolyalkene having from about 9 to about 200 carbon atoms and a secondamount of an unsaturated acidic reagent in the presence of a secondamount of a free radical initiator and in the presence of the firstliquid polyalkene/UAR copolymer of step (a) to form a mixture of a firstand a second liquid polyalkene/UAR copolymer and (c) esterifying themixture of first and second liquid polyalkene/UAR copolymers with apolyol to provide an esterified liquid polyalkene/UAR copolymer product.

A further embodiment of the present invention is a lubricating oilcomposition which comprises a major amount of an oil of lubricatingviscosity and a minor effective amount of the foregoing esterifiedpolyalkene/UAR copolymer reaction products. Also provided by the presentinvention is a lubricating oil concentrate comprising about 10 wt. % toabout 90 wt. % of the foregoing esterified polyalkene/UAR copolymerreaction products and about 90 wt. % to about 10 wt. % of an organicdiluent.

Still yet a further embodiment of the present invention is a fuelconcentrate comprising a major amount of an inert stable oleophilicorganic solvent boiling in the range of about 150° F. to about 400° F.and a minor effective amount of the foregoing esterified polyalkene/UARcopolymer reaction products.

Another embodiment of this invention is a power transmission fluidcomposition comprising a major amount of an oil of lubricating viscosityand a minor effective amount of the foregoing esterified polyalkene/UARcopolymer reaction products. Yet another embodiment is a process forimproving the torque capacity, low temperature operability andanti-shudder durability of a power transmission composition whichcomprises incorporating a minor effective amount of the foregoingesterified polyalkene/UAR copolymer reaction products into a powertransmission composition.

Another embodiment of the present invention is a fuel compositioncomprising (a) a major amount of a hydrocarbon fuel and (b) a minor fueleconomy improving effective amount of the foregoing esterifiedpolyalkene/UAR copolymer reaction products. Yet another embodiment is aprocess for improving the fuel economy of a diesel engine fuel whichcomprises operating the diesel engine with a fuel composition comprising(a) a major amount of a diesel fuel and (b) a minor fuel economyimproving effective amount of the foregoing esterified polyalkene/UARcopolymer reaction products.

The foregoing esterified polyalkene/UAR copolymer reaction products mayalso be post treated with one or more cyclic carbonates or one or morelinear mono- or poly-carbonates under reactive conditions to form one ormore post-treated dispersants. A preferred cyclic carbonate is ethylenecarbonate. This post-treated dispersant may be part of a lubricating oilcomposition comprising a major amount of an oil of lubricating viscosityand a minor effective amount of the post-treated dispersant. Alsoprovided is a lubricating oil concentrate comprising about 90 wt. % toabout 10 wt. % of an oil of lubricating viscosity and about 10 wt. % toabout 90 wt. % of the post-treated dispersant. The foregoing esterifiedpolyalkene/UAR copolymer reaction products may also be post-treated withone or more of boron oxide, boron halide, boric acid, and esters ofboric acid under reactive conditions to form one or more post-treateddispersants which can be employed in a lubricating oil composition orlubricating oil concentrate.

Also provided by the present invention is a fuel concentrate comprisingan inert stable oleophilic organic solvent boiling in the range of about150° F. to about 400° F. and about 5 to about 70 wt. % of the foregoingesterified polyalkene/UAR copolymer reaction products.

The foregoing esterified polyalkene/UAR copolymer reaction products andparticularly the esterified PIB/UAR copolymer reaction products of thepresent invention advantageously provide high torque capacity withoutcausing shudder when employed in a transmission composition. Thesereaction products are also useful when employed in lubricants and fuels.

DEFINITIONS

As used in the present disclosure, whether or not capitalized, thefollowing terms have the following meanings unless specifically statedotherwise.

The term “PIB” is an abbreviation for polyisobutene.

The term “UAR” is an abbreviation for unsaturated acidic reagent(s).

The expression “PIB/UAR copolymer” as used herein shall be understood tomean a copolymer prepared using PIB and unsaturated acidic reagent.

The expression “molecular weight” as used herein shall be understood tomean number average molecular weight (M_(n)).

The expression “degree of polymerization” expresses the length of apolymer or 1:1 copolymer and refers to the number of repeating(monomeric) units in the chain. The number average molecular weight of apolymer or 1:1 copolymer is the product of the degree of polymerizationand the number average molecular weight of the repeating unitmonomer(s). Accordingly, the average degree of polymerization iscalculated by dividing the number average molecular weight of thepolymer by the number average molecular weight of the repeating unitmonomer(s).

The term “alkylvinylidene” or the expression “alkylvinylidene isomer”refers to olefins and polyalkylene components having the followingvinylidene structure (A)

wherein R is a polyalkyl group having about 9 to about 200 carbon atomsand R′ is an alkyl of about 1 to about 6 carbon atoms.

The expression “chain transfer agent” as used herein shall be understoodto mean an agent that will provide an active hydrogen or halogen thatcan be abstracted during a polymerization reaction. Chain transferreactions stop a growing chain radical and start a new one in its place.Thus chain transfer results in shorter chains, lower degree ofpolymerization and lower molecular weights. Typical chain transferagents may include mercaptans, aromatic compounds with benzylichydrogens, and halogenated hydrocarbons such as carbon tetrachloride andcarbon tetrabromide.

The term “SAP” refers to Saponification Number and may be determined bythe procedure described in ASTM D94 or any other equivalent procedure.

The term “TAN” refers to Total Acid Number and may be determined by theprocedure described in ASTM D 664 or any other equivalent procedure.

The expression “succinic ratio” may be calculated from thesaponification number (mg KOH per gram of sample), the actives contentof the alkenyl or alkyl succinic anhydride product and the molecularweight of the starting polyolefin. The actives content of the alkenyl oralkyl succinic anhydride product is measured in terms of the activesfraction, wherein an actives fraction of 1.0 is equivalent to 100 weightpercent actives. Accordingly, an actives fraction of 0.5 wouldcorrespond to 50 weight percent actives.

The succinic ratio of the alkenyl or alkyl succinic anhydride product ofmaleic anhydride and polyolefin can be calculated in accordance with thefollowing equation:

${{Succinic}\mspace{14mu} {ratio}} = \frac{M_{po} \times P}{\left( {C \times A} \right) - \left( {M_{ma} \times P} \right)}$

wherein

-   P=saponification number of the alkenyl or alkyl succinic anhydride    sample (mg KOH/g)-   A=actives fraction of the alkenyl or alkyl succinic anhydride sample-   M_(po)=number average molecular weight of the starting polyolefin-   M_(ma)=98 (molecular weight of maleic anhydride)-   C=conversion factor=12220 (for conversion of gram-moles of alkenyl    or alkyl succinic anhydride per gram of sample to milligrams of KOH    per gram of sample).

The actives fraction of the alkenyl or alkyl succinic anhydride may bedetermined from the percent of unreacted polyolefin according to thefollowing procedure. A 5.0 gram sample of the reaction product of maleicanhydride and polyolefin is dissolved in hexane, placed in a column of80.0 grams of silica gel (Davisil 62, a 140 angstrom pore size silicagel), and eluted with 1 liter of hexane. The percent unreactedpolyolefin is determined by removing the hexane solvent under vacuumfrom the eluent and weighing the residue. Percent unreacted polyolefinis calculated according to the following formula:

${{Percent}\mspace{14mu} {Unreacted}\mspace{14mu} {Polyolefin}} = {\frac{{Net}\mspace{14mu} {Weight}\mspace{14mu} {of}\mspace{14mu} {Residue}}{{Sample}\mspace{14mu} {Weight}} \times 100}$

The weight percent actives for the alkenyl or alkyl succinic anhydrideproduct is calculated from the percent unreacted polyolefin using theformula:

Weight Percent Actives=100−Percent Unreacted Polyolefin

The actives fraction of the alkenyl or alkyl succinic anhydride is thencalculated as follows:

${{Actives}\mspace{14mu} {Fraction}} = {\frac{{Weight}\mspace{14mu} {Percent}\mspace{14mu} {Actives}}{100}.}$

The term “PTB” as used herein shall be understood to mean pounds perthousand barrels.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph of the coefficient of friction versus number of cyclesillustrating the frictional properties of the automatic transmissionfluid of Example 5 versus the automatic transmission fluid ofComparative Example A; and,

FIG. 2 is an IR spectra of the esterified PIB/UAR copolymer of Example2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In accordance with the present invention, esterified copolymer reactionproducts referred to herein as the esterified polyalkene/UAR copolymerreaction products and particularly the esterified PIB/UAR copolymerreaction products are provided. The esterified polyalkene/UAR copolymermay be obtained as the reaction product of a polyalkene/UAR copolymerwith a polyol, each of which are described herein below.

The Copolymers

The polyalkene/UAR copolymers for use in preparing the esterifiedpolyalkene/UAR copolymers of the present invention possess the generalformula (I):

wherein X and X′ in each repeating unit of the copolymer areindependently selected from the group consisting of —OH; —O—R₃ whereinR₃ is a lower alkyl of 1 to 6 carbon atoms; or taken together are —O— toform a succinic anhydride group; n is a whole integer from 1 to 3; R₁ isa lower alkyl of 1 to 6 carbon atoms; R₂ is a polyalkyl group havingabout 9 to about 200 carbon atoms; m is a whole integer of from 1 to 3;x is a number greater than 1 up to 20; Int. is at least one initiatingradical; and Ter. is at least one terminating group; and wherein thecopolymer has a succinic ratio of about 1. Representative examples ofthese copolymers include those described in U.S. Pat. Nos. 5,112,507 and5,616,668, the contents of which are incorporated by reference herein.

In a preferred embodiment, when maleic anhydride is used as theunsaturated acidic reagent, the reaction produces polyalkene/UARcopolymers predominately of the following formula (II):

wherein R₁, R₂, n, m, x, Int. and Ter. are as defined above.

Generally, such copolymers contain an initiator group, Int., and aterminator group, Ter., as a result of the reaction with the freeradical initiator used in the polymerization reaction. In such a case,the initiator and terminator groups may be:

wherein R⁵ is hydrogen, alkyl, aryl, alkaryl, aralkyl, cycloalkyl,alkoxy, cycloalkoxy, acyl, alkenyl, cycloalkenyl, alkynyl; or alkyl,aryl, alkaryl or aralkyl optionally substituted with 1 to 4 substituentsindependently selected from nitrile, keto, halogen, nitro, alkyl, aryl,and the like; and R⁶ and R⁷ are independently hydrogen, alkyl, aryl,alkaryl, aralkyl and the like. Alternatively, the initiator group and/orterminator group may be derived from the reaction product of theinitiator with another material such as solvent; for example, theinitiator may react with toluene to produce a benzyl radical.

The polyalkene/UAR copolymers have an average degree of polymerizationof about 1.1 to about 20, and more preferably from about 1.5 to about 5.The polyalkene/UAR copolymers have a number average molecular weight ofabout 600 to about 30000 and preferably from about 650 to about 3000.The polyalkene/UAR copolymer may be alternating or random. Preferably,the polyalkene/UAR copolymer is an alternating copolymer.

A(1) The Polyalkene

The polyalkene employed in the preparation of the polyalkene/UARcopolymer is an olefin of sufficiently long chain length so that theresulting copolymer composition is soluble in and compatible withmineral oils, fuels and the like.

Olefins suitable for use herein are generally mixtures of moleculeshaving different molecular weights and can have at least one branch per6 carbon atoms along the chain, preferably at least one branch per 4carbon atoms along the chain, and particularly preferred that there beabout one branch per 2 carbon atoms along the chain. These branchedchain olefins may conveniently comprise polyalkenes prepared by thepolymerization of olefins of, for example, from 3 to 6 carbon atoms, andpreferably from olefins of from 3 to 4 carbon atoms, and more preferablyfrom propylene or isobutylene. The additional-polymerizable olefinsemployed are normally 1-olefins. The branch may be of from 1 to 4 carbonatoms, more usually of from 1 to 2 carbon atoms and preferably methyl.

In general, the polyalkene can contain both alkylvinylidene isomer andnon-alkylvinylidene isomers with the alkylvinylidene isomer of theolefin preferably comprising at least about 20% of the total olefincomposition. Preferably, the polyalkene is a polybutene, more preferablya polyisobutene, and most preferably a polyisobutene wherein at least20%, but less than 100%, of the polyisobutene has methylvinylidene endgroups. Typical PIBs for use in forming the esterified PIB/UARcopolymers of the present invention will contain about 9 to about 200carbon atoms. More preferred PIBs contain from about 15 to about 100carbon atoms, even more preferably from about 24 to about 80 carbonatoms and most preferably from about 28 to about 50 carbon atoms.

The olefinic bonds of a preferred PIB may comprise about 20% or more,preferably about 50% or more, and more preferred about 80% or more ofthe alkylvinylidene isomer. Accordingly, preferred PIB/UAR copolymersinclude those in which an unsaturated acidic reagent, most preferablymaleic anhydride, is copolymerized with a PIB and wherein about 20% ormore, preferably about 50% or more, and more preferred about 80% or moreof the olefinic bonds of the PIB comprises alkylvinylidene.

The olefinic bonds of a more preferred PIB may comprise about 20% ormore, preferably about 50% or more, and more preferred about 80% or moreof the methylvinylidene isomer. Accordingly, more preferred PIB/UARcopolymers include those in which an unsaturated acidic reagent, mostpreferably maleic anhydride, is copolymerized with a PIB wherein about20% or more, preferably about 50% or more, and more preferred about 80%or more of the olefinic bonds of the PIB comprises methylvinylidene.

Preferred PIBs include those PIBs prepared using a boron triflouride(BF₃) catalyst. The preparation of PIBs in which the methylvinylideneisomer comprises a high percentage of the total composition is describedin U.S. Pat. Nos. 4,152,499 and 4,605,808. PIB may be prepared directlyor may be a distilled fraction of higher molecular weight polybutene.

PIB/UAR copolymers may comprise a mixture of PIB molecules of varyingmolecular weight because PIBs used to prepare PIB/UAR copolymers aregenerally mixtures of individual molecules of different molecularweights, e.g., PIBs having a number average molecular weight (M_(n)) ofabout 126 to 2800. Preferred PIBs have a number average molecular weightof about 210 to about 1400. Even more preferred PIBs have a numberaverage molecular weight of about 336 to about 1120. Most preferred PIBhas a number average molecular weight of about 350 to about 700. Also,the PIB/UAR copolymer may comprise a PIB/UAR copolymer molecules havingdifferent degrees of polymerization.

The polyalkene used to prepare the polyalkene/UAR copolymer can also beused in combination with a 1-olefin (also known as an “alpha-olefin”).Suitable 1-olefins for use herein typically possess at least two carbonatoms, preferably five or more carbon atoms, and most preferably about10 to about 30 carbon atoms. U.S. Pat. No. 5,792,729 discloses thepreparation of terpolymers made from a polyalkene, a 1-olefin, and anunsaturated acidic reagent and is incorporated by reference herein.

A(2) The Unsaturated Acidic Reagent

The unsaturated acidic reagent for use in reacting with the foregoingpolyalkenes can be any ethylenically unsaturated carboxylic acid orsource of carboxylic acid functionality. These reactants typicallycontain at least one ethylenic bond and at least one and preferably twocarboxylic acid groups, an anhydride group or a polar group which isconvertible into a carboxylic acid group by oxidation or hydrolysis.Preferably the unsaturated acidic reagent refers to maleic or fumaricreagents of the general formula:

wherein X and X′ are the same or different, provided that at least oneof X and X′ is a group that is capable of reacting to esterify alcohols,form metal salts with reactive metals or basically reacting metalcompounds and otherwise function as acylating agents. Typically, X andX′ comprise functional groups that may comprise one or more of —OH;—O—R₃ wherein R₃ is a lower alkyl of 1 to 6 carbon atoms; or takentogether X and X′ may be —O— so as to form an anhydride. Preferably, Xand X′ are such that both carboxylic functions can enter into acylationreactions. Suitable unsaturated acidic reagents include, but are notlimited to, electron-deficient olefins such as maleic anhydride, maleicacid, maleic acid monoesters and diesters, fumaric acid, and fumaricacid monoesters and diesters.

A(3) Free Radical Initiator

A free radical initiator is an organic or inorganic substance that underreaction conditions will decompose to molecular fragment(s) having oneor more unpaired electrons that are capable of initiating apolymerization reaction. Any free radical initiator may initiate thecopolymerization described herein. Such initiators are well known in theart. However, the choice of free radical initiator may be influenced bythe reaction temperature used in forming the polyalkene/UAR copolymer.Preferably, the free radical initiators for use herein are of theperoxide-type polymerization initiators and the azo-type polymerizationinitiators. If desired, radiation may also be used to initiate thereaction.

Suitable peroxide-type free radical initiators may be organic orinorganic radicals. Useful organic free radical initiators may have thegeneral formula: R⁸OOR⁹ wherein R⁸ is any organic radical and R⁹ is oneor more of hydrogen and any organic radical. Both R⁸ and R⁹ may beorganic radicals, preferably hydrocarbon, aroyl, and acyl radicals,carrying, if desired, substituents such as, for example, halogens.Preferred peroxides include di-tert-butyl peroxide, tert-butylperoxybenzoate, and dicumyl peroxide.

Examples of other suitable peroxides include, but are not limited to,benzoyl peroxide; lauroyl peroxide; other tertiary butyl peroxides;2,4-dichlorobenzoyl peroxide; tertiary butyl hydroperoxide; cumenehydroperoxide; diacetyl peroxide; acetyl hydroperoxide;diethylperoxycarbonate; tertiary butyl perbenzoate; and the like.

Useful azo-type compounds, typified byalpha,alpha′-azobisisobutyronitrile, are also well-known free radicalpromoting materials. These azo compounds may be defined as those havingpresent in the molecule group —N═N— wherein organic radicals satisfy thebalance, at least one of which is preferably attached to a tertiarycarbon. Other suitable azo compounds include, but are not limited to,p-bromobenzenediazonium fluoroborate; p-tolyldiazoaminobenzene;p-bromobenzenediazonium hydroxide; azomethane and phenyldiazoniumhalides. Representative of the azo-type compounds are those disclosed inU.S. Pat. No. 2,551,813, the content of which are incorporated herein byreference.

The amount of free radical initiator to employ, exclusive of radiation,depends to a large extent on the particular initiator selected, themolecular weight PIB used and the reaction conditions. A preferredinitiator is one that is soluble in the reaction medium. Preferredconcentrations of initiator may be between about 0.001:1 and about 0.2:1moles of initiator per mole of polyalkene, with preferred amountsbetween about 0.005:1 and about 0.10:1 moles.

It is preferred that the polymerization temperature is sufficiently highto break down the free radical initiator to produce the desired freeradicals. The half-life values for known free radical initiators atvarious temperatures are readily available from the literature. See, forexample, C. Walling, “Free Radicals in Solution”, John Wiley and Sons,Inc., New York (1957). Alternatively, the half-life values are availablefrom the various suppliers of free radical initiators. Table I lists thehalf-life temperatures for a number of free radical initiators at agiven half-life. The half-life temperature is the temperature requiredfor a free radical initiator to exhibit a specified half-life. As arule, the higher the half-life temperature, the lower the half-life ofthe free radical initiator.

TABLE I HALF-LIFE TEMPERATURES OF VARIOUS FREE RADICAL INITIATORS ATSPECIFIED HALF-LIVES Half-Life (Temperature in degrees C.) Free RadicalInitiators 5 Min. 10 Min. 2 Hrs. 5 Hrs. 10 Hrs. Dialkyl Peroxides: 173166 143 135 129 di-t-butyl peroxide di-t-amyl peroxide 167 160 137 129123 di-cumyl peroxide 161 154 131 123 117 2,5-dimethyl-2, 164 157 134126 120 5-di(t-butylperoxy) 134 128 106 99 93 hexane Peroxyketals:1,1-di-tannylperoxy- Cyclohexane 85 79 60 54 49 Diperoxycarbonates:di-ethylhexylperoxy- Dicarbonate 102 96 76 69 64 Diacyl Peroxides:didecanoyl peroxide

In preparing the polyalkene/UAR copolymer, a single free radicalinitiator or a mixture of free radical initiators can be employed. Forexample, it may be desirable to add an initiator having a lowdecomposition temperature as the mixture of PIB and UAR is warming toreaction temperature, and then add an initiator having a higherdecomposition temperature as the mixture reaches higher reactiontemperatures. Alternatively, a combination of initiators could both beadded prior to heating and reaction. In this case, an initiator having ahigh decomposition temperature would initially be inert, but would laterbecome active as the temperature rose.

The initiator can also be added over time. For example, if an initiatoris chosen with a short half-life, e.g., about 5 to about 20 minutes, atthe reaction temperature, then the initiator can be added over a periodof time so that an adequate concentration of free radicals will beavailable throughout the reaction period to give improved yields of thedesired product.

A(4) General Preparation of the Copolymer

The foregoing polyalkene/UAR copolymers can be prepared by reacting oneor more of the foregoing polyalkenes with one or more of the foregoingunsaturated acidic reagents in the presence of one or more of theforegoing free radical initiators.

In general, the reaction can be conducted neat, that is, thepolyalkene(s), the unsaturated acidic reagent(s) and the free radicalinitiator(s) are combined in the proper ratio, and then stirred at thereaction temperature. The reaction time is typically a time sufficientto result in the substantially complete conversion of the reactiveisomers of the polyalkene to the polyalkene/UAR copolymer. Suitablereaction times ordinarily range from about one hour to about 24 hoursand preferably from about two to about ten hours.

Polymerization or copolymerization of the polyalkene(s) and unsaturatedacidic reagent(s) in the presence of the free radical initiator(s) canbe carried out in any known manner, e.g., in the liquid phase, i.e., ina solution or slurry process, or in a suspension process, eithercontinuously or in batch. The important factors are intimate contact ofthe polyalkene and unsaturated acidic reagent in the presence of thefree radical initiator. The components in the reaction mixture can alsobe added continuously to a stirred reactor with continuous removal of aportion of the product to a recovery train or to other reactors inseries. The reaction can also take place in a tubular reactor in whichthe components can be added at one or more points along the tube.

The reaction is generally carried out at temperatures in the range offrom about −30° C. to about 210° C. and preferably from about 40° C. toabout 150° C., and pressures from about 0 to about 40 psig. As oneskilled in the art would readily appreciate, it is preferred that thepolymerization temperature is sufficiently high to decompose the freeradical initiator to produce the desired free radicals. For example,using benzoyl peroxide as the initiator, the reaction temperature can bebetween about 75° C. to about 90° C. and preferably between about 80° C.to about 85° C. The degree of polymerization is inversely proportionalto the temperature. Thus, higher reaction temperatures are ordinarilypreferred for preparing polyalkene/UAR copolymers with a particularlylow degree of polymerization. In general, after the reaction is deemedcomplete by, for example, NMR analysis, the reaction mixture is heatedto decompose any residual initiator. For a di-tert-butyl peroxideinitiator, this temperature is generally about 16° C. or higher.

When the polyalkene, unsaturated acidic reagent and free radicalinitiator react to provide a polyalkene/UAR copolymer, thepolyalkene/UAR copolymer that is formed assists in dissolving theunsaturated acidic reagent. This facilitates the reaction of unreactedpolyalkene, unsaturated acidic reagent and free radical initiator. Inlight of this phenomenon, previously formed polyalkene/UAR copolymersmay be used to facilitate new reactions of polyalkene, unsaturatedacidic reagent and free radical initiator reactants. Using thepolyalkene/UAR copolymer to facilitate this reaction is referred toherein as the heel process.

A preferred process to use the polyalkene/UAR copolymer in the heelprocess is to combine the polyalkene, unsaturated acidic reagent andpolyalkene/UAR copolymer; heat this combination to reaction temperature;and then add the free radical initiator while maintaining a suitablereaction temperature. This process can be conducted in batch or incontinuous mode.

The polyalkene/UAR copolymer for use in the heel process can be obtainedby retaining a portion of the polyalkene/UAR copolymer from a previousrun. Preferred polyalkene/UAR copolymers for use in the heel processinclude the copolymer product of PIB and maleic anhydride. The preferredvolume ratio of PIB/UAR copolymer to PIB in the heel process is betweenabout 1:20 and 1:1. A more preferred volume ratio of PIB/UAR copolymerto PIB in the heel process is between about 1:10 and about 1:5.

The heel process reaction is advantageously conducted at a temperaturein the range of about 90° C. to about 210° C. and more preferably fromabout 130° C. to about 150° C. At lower reaction temperatures thereaction mixture may become too viscous and may require a solvent toobtain satisfactory reaction.

The unsaturated acidic reagent charge may theoretically range from about0.5 to about 2 moles of unsaturated acidic reagent per mole of methylvinylidene isomer of PIB. Typically, the free radical initiator may becharged at about 0.01 moles initiator per about 0.05 moles polyalkene,although this may vary. The reaction can be carried out at atmosphericpressure. At higher temperatures, it is desirable to pressurize thereactor slightly (i.e., about 10 psig) to suppress the loss ofunsaturated acidic reagent to the vapor phase.

If a batch reaction is used, PIB/UAR copolymer from a previous run andPIB can be charged to the reactor. A sufficient ratio of PIB to PIB/UARcopolymer to assure complete solubility of unsaturated acidic reagent inthe mixture at reaction conditions is preferred. If PIB/UAR copolymer isnot added at a sufficient level so as to maintain total unsaturatedacidic reagent solubility, the rate of reaction may be negativelyaffected, and the formation of resin may be likely. To maximize reactorproductivity, the minimum amount of PIB/UAR copolymer that is optimal tomaintain total solubility of the unsaturated acidic reagent chargeshould be used. The reactor can be stirred and heated to the desiredreaction temperature, and the unsaturated acidic reagent and freeradical initiator are added at the appropriate time/times during thisstep. Reaction times will vary according to such factors as, forexample, temperature, concentration of reactants, and types of freeradical initiators. When the reaction is complete, removal of anyunreacted unsaturated acidic reagent can be accomplished by increasingthe reactor temperature to about 150° C. to about 250° C. and preferablyfrom about 180° C. to about 200° C., while applying sufficient vacuum.This procedure also tends to decompose any remaining free radicalinitiator.

If the reaction is run continuously, a continuous stirred tank reactor(CSTR) or series of such reactors can be employed. Accordingly, PIB,unsaturated acidic reagent, and free radical initiator can be fedcontinuously at appropriate rates so as to maintain a certain level ofconversion of the reactants to PIB/UAR copolymer. It is envisioned thatthe product stream from the reactor then is heated to a temperature inthe range of about 150° C. to about 250° C. and preferably in the rangefrom about 180° C. to about 200° C. to strip off any unreactedunsaturated acidic reagent and to decompose any remaining free radicalinitiator. Vacuum can also be used to facilitate removing any unreactedunsaturated acidic reagent. It is also envisioned that a wiped filmevaporator or similar types of equipment are suitable for this type ofoperation. In general and as discussed above, after the reaction isdeemed complete the reaction mixture is heated to decompose any residualinitiator.

The reaction can be carried out in the absence of a diluent or, ifdesired, in the presence of a diluent. When a diluent is employed, thosediluents that are inert to the reactants and products formed arepreferred.

Although a solvent is not necessary to prepare the PIB/UAR copolymer,one can be used. Solvents that can be employed are those that are inertto the reactants and products formed. Suitable solvents include theketones having from three to six carbon atoms and the saturateddehalogenated hydrocarbons having from one to five, more preferably oneto three, carbon atoms. Examples of suitable solvents include, but arenot limited to:

1. ketones, such as: acetone; methylethylketone; diethylketone; andmethylisobutylketone;

2. aromatic hydrocarbons, such as: benzene; xylene; and toluene;

3. saturated dihalogenated hydrocarbons, such as: dichloromethane;dibromomethane; 1-bromo-2-chloroethane; 1,1-dibromoethane;1,1-dichloroethane; 1,2-dichloroethane; 1,3-dibromopropane;1,2-dibromopropane; 1,2-dibromo-2-methylpropane; 1,2-dichloropropane;1,1-dichloropropane; 1,3-dichloropropane; 1-bromo-2-chloropropane;1,2-dichlorobutane; 1,5-dibromopentane; and 1,5-dichloropentane; or

4. mixtures of the above, such as: benzene or methylethylketone.Suitable solvents include, but are not limited to, acetone,tetrahydrofuran, chloroform, methylene chloride, dichloroethane,toluene, dioxane, chlorobenzene, xylenes, or the like. Solvents can beremoved after their usefulness is no longer required. The PIB/UARcopolymer product can be conveniently separated from any solvent usedand any unreacted acidic reagent by conventional procedures, e.g., byphase separation, solvent distillation, precipitation and the like.Though not required, dispersing agents and/or co-solvents can be usedduring the reaction.

Although a chain transfer agent to prepare the PIB/UAR copolymer of thisinvention is not required, one can be used when desired. Typically,chain transfer agents that are inert to the reactants and productsformed are preferred are used herein.

The Esterified Copolymers

The preferred esterified polyalkene/UAR copolymers of the presentinvention are a reaction product of a polyol and a copolymer of thegeneral formula (I):

wherein X and X′ in each repeating unit of the copolymer areindependently selected from the group consisting of —OH; —O—R₃ whereinR₃ is a lower alkyl of 1 to 6 carbon atoms; or taken together are —O— toform a succinic anhydride group; n is a whole integer from 1 to 3; R₁ isa lower alkyl of 1 to 6 carbon atoms; R₂ is a polyalkyl having fromabout 9 to about 200 carbon atoms; m is a whole integer of from 1 to 3;x is a number greater than 1 up to 20; Int. is at least one initiatingradical; and Ter. is at least one terminating group; and wherein thecopolymer has a succinic ratio of about 1. The PIB/UAR copolymers priorto esterification typically have an average degree of polymerization ofabout 1.1 to about 20, preferably from about 1.5 to about 10 and morepreferably from about 2 to about 8. The esterified PIB/UAR copolymersmay have a number average molecular weight of about 600 to about 30,000,preferably 1,000 to 25,000, even more preferably 5,000 to 25,000 andmost preferably 10,000 to 20,000.

The esterified polyalkene/UAR copolymer reaction products of the presentinvention can be prepared by reacting the foregoing polyalkene/UARcopolymers with an effective amount of one or more polyols underesterification reaction conditions. Suitable polyols for use herein havethe formula R″(OH)_(y) where R″ is a hydrocarbon radical and y is aninteger representing the number of hydroxy radicals and has a value offrom 2 to about 10. The polyols preferably contain less than about 12carbon atoms, and have from 2 to about 10 and preferably 3 to 6, hydroxyradicals. Examples of suitable polyols include alkylene glycols andpoly(oxyalkylene) glycols, e.g., ethylene glycol, di(ethylene glycol),tri(ethylene glycol), di(propylene glycol), tri(butylene glycol),penta(ethylene glycol), and other poly(oxyalkylene) glycols formed bythe condensation of two or more moles of ethylene glycol, propyleneglycol, octylene glycol, or a like glycol having up to 12 carbon atomsin the alkylene radical. Other useful polyols include, but are notlimited to, glycerol, pentaerythritol, 2,4-hexanediol, pinacol,erythritol, arabitol, sorbitol, mannitol, 1,2-cyclohexanediol, xylyleneglycol, and 1,3,5-cyclohexanetriol. One preferred polyol ispentaerythritol. Other useful polyols are disclosed in U.S. Pat. No.4,034,038, the contents of which are incorporated herein by reference.Esterification can be advantageously effected at a temperature of about100° C. to about 220° C. and preferably from about 150° C. to about 200°C. Ordinarily, the reaction is carried out at substantially atmosphericpressure, although pressures above atmospheric can be employed with morevolatile reactants. The reaction can be carried out in the absence of acatalyst, or in the presence of an acid-type catalyst such as, forexample, mineral acids, sulfonic acids, Lewis type acids and the like.Suitable reaction conditions and catalysts are disclosed in U.S. Pat.No. 3,155,686, the contents of which are incorporated herein byreference. Concentration of polyol will ordinarily range from about 0.1to about 1, preferably from about 0.5 to about 0.8 and most preferablyabout 0.75 times the number of anhydride units as measured by the SAPnumber. Unreacted polyol must be removed by any conventional technique,for example, filtration.

When the polyalkene/UAR copolymers and particularly the PIB/maleicanhydride copolymers are esterified to form the reaction products of thepresent invention, the resulting reaction product will contain ester,acid, and anhydride functional groups. Among other factors, it isexpected that the internal anhydride units, within the copolymer, arenot reactive towards esterification. Thus, as one skilled in the artwould readily appreciate, the copolymer is partially esterified, e.g.,the esterification of the copolymers being continued to such an extentthat about 1 to about 99%, preferably from about 20 to about 80% andmost preferably from about 40 to about 70% of the carboxyl groups of thecopolymers are esterified.

Post-Treatments

The foregoing esterified polyalkene/UAR copolymer reaction products canbe post-treated with a wide variety of post-treating reagents. Forexample, the dispersancy of the esterified polyalkene/UAR copolymers ofthe present invention can be improved by reaction with a cycliccarbonate

The cyclic carbonate post-treatment may be conducted under conditionssufficient to cause reaction of the cyclic carbonate with free hydroxylgroups within the esterified polyalkene/UAR copolymers. The reaction isordinarily conducted at temperatures ranging from about 100° C. to about220° C., preferably from about 150° C. to about 200° C.

The reaction may be conducted neat, wherein both the esterifiedcopolymer reaction product and the cyclic carbonate are combined in theproper ratio. The same solvents or diluents as described above withrespect to the preparing the esterified PIB/UAR copolymer may also beused in the cyclic carbonate post-treatment.

A particularly preferred cyclic carbonate for use herein is1,3-dioxolan-2-one (ethylene carbonate).

The cyclic carbonate post-treatment can be advantageously effected at atemperature of about 100° C. to about 220° C. and preferably from about150° C. to about 200° C. Ordinarily, the reaction is carried out atsubstantially atmospheric pressure, although pressures above atmosphericcan be employed with more volatile reactants. Concentration of cycliccarbonate will ordinarily range from about 0.1 to about 1, preferablyfrom about 0.5 to about 0.8 times the number of moles of polyol employedin the esterification reaction step.

The foregoing esterified polyalkene/UAR copolymer reaction products andthe post-treated foregoing esterified PIB/UAR copolymer reactionproducts of this invention can be further reacted with boric acid or asimilar boron compound such as, for example, boron oxides, boron halidesand esters of boric acid, to form borated dispersants having utilitywithin the scope of this invention. Generally from about 0.1 equivalentsto about 10 equivalents and preferably from about 0.2 equivalents toabout 1 equivalents of boron compound per equivalents of hydroxyl in theesterified PIB/UAR copolymer can be used.

Lubricating Oil Compositions

The esterified polyalkene/UAR copolymer and post-treated esterifiedpolyalkene/UAR copolymer reaction products of the present invention areuseful as additives when used in lubricating oil compositions such as,for example, power transmission fluids. When the foregoing esterifiedpolyalkene/UAR copolymer and post-treated esterified polyalkene/UARcopolymer reaction products of the present invention are used as afriction modifier in, for example, a power transmission fluidcomposition containing a major amount of an oil of lubricatingviscosity, the friction modifier is ordinarily present in thecomposition in a minor effective amount ranging from about 0.1 to about10 wt. %, preferably from about 0.5 wt. % to about 5% wt. % and morepreferably at about 1 wt. % to about 3 wt. %, based on the total weightof the lubricating oil composition.

The oils of lubricating viscosity for use in a lubricating oilcomposition such as, for example, a power transmission fluid, areselected from one or more natural oils, synthetic oils or mixturesthereof. Useful natural oils include mineral lubricating oils such as,for example, liquid petroleum oils, solvent-treated or acid-treatedmineral lubricating oils of the paraffinic, naphthenic or mixedparaffinic-naphthenic types, oils derived from coal or shale, animaloils, vegetable oils (e.g., castor oils and lard oil), and the like.

Useful synthetic lubricating oils include, but are not limited to,hydrocarbon oils and halo-substituted hydrocarbon oils such aspolymerized and interpolymerized olefins, e.g., polybutylenes,polypropylenes, propylene-isobutylene copolymers, chlorinatedpolybutylenes, poly(1-hexenes), poly(1-octenes), poly(1-decenes), andthe like and mixtures thereof; alkylbenzenes such as dodecylbenzenes,tetradecylbenzenes, dinonylbenzenes, di(2-ethylhexyl)-benzenes, and thelike; polyphenyls such as biphenyls, terphenyls, alkylated polyphenyls,and the like; alkylated diphenyl ethers and alkylated diphenyl sulfidesand the derivative, analogs and homologs thereof and the like.

Other useful synthetic lubricating oils include, but are not limited to,oils made by polymerizing olefins of less than 5 carbon atoms such asethylene, propylene, butylenes, isobutene, pentene, and mixturesthereof. Processs of preparing such polymer oils are well known to thoseskilled in the art.

Additional useful synthetic hydrocarbon oils include liquid polymers ofalpha olefins having the proper viscosity. Especially useful synthetichydrocarbon oils are the hydrogenated liquid oligomers of C₆ to C₁₂alpha olefins such as, for example, 1-decene trimer.

Another class of useful synthetic lubricating oils include, but are notlimited to, alkylene oxide polymers, i.e., homopolymers, interpolymers,and derivatives thereof where the terminal hydroxyl groups have beenmodified by, for example, esterification or etherification. These oilsare exemplified by the oils prepared through polymerization of ethyleneoxide or propylene oxide, the alkyl and amyl ethers of thesepolyoxyalkylene polymers (e.g., methyl poly propylene glycol etherhaving an average molecular weight of 1,000, diphenyl ether ofpolyethylene glycol having a molecular weight of 500-1000, diethyl etherof polypropylene glycol having a molecular weight of 1,000-1,500, etc.)or mono- and polycarboxylic esters thereof such as, for example, theacetic esters, mixed C₃-C₈ fatty acid esters, or the C₁₃Oxo acid diesterof tetraethylene glycol.

Yet another class of useful synthetic lubricating oils include, but arenot limited to, the esters of dicarboxylic acids e.g., phthalic acid,succinic acid, alkyl succinic acids, alkenyl succinic acids, maleicacid, azelaic acid, suberic acid, sebacic acid, fumaric acid, adipicacid, linoleic acid dimer, malonic acids, alkyl malonic acids, alkenylmalonic acids, etc., with a variety of alcohols, e.g., butyl alcohol,hexyl alcohol, dodecyl alcohol, 2-ethylhexyl alcohol, ethylene glycol,diethylene glycol monoether, propylene glycol, etc. Specific examples ofthese esters include dibutyl adipate, di(2-ethylhexyl)sebacate,di-n-hexyl fumarate, dioctyl sebacate, diisooctyl azelate, diisodecylazelate, dioctyl phthalate, didecyl phthalate, dieicosyl sebacate, the2-ethylhexyl diester of linoleic acid dimer, the complex ester formed byreacting one mole of sebacic acid with two moles of tetraethylene glycoland two moles of 2-ethylhexanoic acid and the like.

Esters useful as synthetic oils also include, but are not limited to,those made from monocarboxylic acids having from about 5 to about 12carbon atoms and polyols and polyol ethers such as neopentyl glycol,trimethylol propane, pentaerythritol, dipentaerythritol,tripentaerythritol, and the like.

Silicon-based oils such as, for example, polyalkyl-, polyaryl-,polyalkoxy- or polyaryloxy-siloxane oils and silicate oils, compriseanother useful class of synthetic lubricating oils. Specific examples ofthese include, but are not limited to, tetraethyl silicate,tetra-isopropyl silicate, tetra-(2-ethylhexyl) silicate,tetra-(4-methyl-hexyl)silicate, tetra-(p-tert-butylphenyl)silicate,hexyl-(4-methyl-2-pentoxy)disiloxane, poly(methyl)siloxanes,poly(methylphenyl)siloxanes, and the like. Still yet other usefulsynthetic lubricating oils include, but are not limited to, liquidesters of phosphorous containing acids, e.g., tricresyl phosphate,trioctyl phosphate, diethyl ester of decane phosphionic acid, etc.,polymeric tetrahydrofurans and the like.

The lubricating oil may be derived from unrefined, refined and rerefinedoils, either natural, synthetic or mixtures of two or more of any ofthese of the type disclosed hereinabove. Unrefined oils are thoseobtained directly from a natural or synthetic source (e.g., coal, shale,or tar sands bitumen) without further purification or treatment.Examples of unrefined oils include, but are not limited to, a shale oilobtained directly from retorting operations, a petroleum oil obtaineddirectly from distillation or an ester oil obtained directly from anesterification process, each of which is then used without furthertreatment. Refined oils are similar to the unrefined oils except theyhave been further treated in one or more purification steps to improveone or more properties. These purification techniques are known to thoseof skill in the art and include, for example, solvent extractions,secondary distillation, acid or base extraction, filtration,percolation, hydrotreating, dewaxing, etc. Rerefined oils are obtainedby treating used oils in processes similar to those used to obtainrefined oils. Such rerefined oils are also known as reclaimed orreprocessed oils and often are additionally processed by techniquesdirected to removal of spent additives and oil breakdown products.

Lubricating oil base stocks derived from the hydroisomerization of waxmay also be used, either alone or in combination with the aforesaidnatural and/or synthetic base stocks. Such wax isomerate oil is producedby the hydroisomerization of natural or synthetic waxes or mixturesthereof over a hydroisomerization catalyst.

Natural waxes are typically the slack waxes recovered by the solventdewaxing of mineral oils; synthetic waxes are typically the wax producedby the Fischer-Tropsch process.

Lubricating oil concentrates are also contemplated herein. Theseconcentrates usually include at least from about 90 wt. % to about 10wt. % and preferably from about 90 wt. % to about 50 wt. %, of an oil oflubricating viscosity and from about 10 wt. % to about 90 wt. %,preferably from about 10 wt. % to about 50 wt. %, of the foregoingesterified polyalkene/UAR copolymer and post-treated esterifiedpolyalkene/UAR copolymer reaction products of the present invention.Typically, the concentrates contain sufficient diluent to make them easyto handle during shipping and storage. Suitable diluents for theconcentrates include any inert diluent, preferably an oil of lubricatingviscosity, so that the concentrate may be readily mixed with lubricatingoils to prepare lubricating oil compositions. Suitable lubricating oilsthat may be used as diluents typically have viscosity in the range fromabout 35 to about 500 Saybolt Universal Seconds (SUS) at 100° F. (38°C.), although any oil of lubricating viscosity may be used.

If desired, other additives can be admixed with the foregoinglubricating oil compositions to enhance performance. Examples of theseadditives include, but are not limited to, rust inhibitors, foaminhibitors, corrosion inhibitors, metal deactivators, pour pointdepressants, antioxidants, wear inhibitors and the like, at the usuallevels in accordance with well known practice.

It is also contemplated that the additives described herein may beemployed as dispersants and detergents in hydraulic fluids, marinecrankcase lubricants and the like. When so employed, the additive isadded at from about 0.1 to 10% by weight to the oil and preferably fromabout 0.5 to about 8% by weight to the oil, based on the total weight ofthe lubricant composition.

Fuel Compositions

The foregoing esterified polyalkene/UAR copolymer reaction products ofthe present invention are also useful as a friction modifier additivefor fuel compositions.

The fuel can be any internal combustion engine hydrocarbon fuel, e.g.,diesel, gasoline, kerosene, jet fuels, etc.; alcoholic fuels such asmethanol or ethanol; or a mixture of any of the foregoing. When the fuelis diesel, such fuel generally boils above about 212° F. The diesel fuelcan comprise atmospheric distillate or vacuum distillate, or a blend inany proportion of straight run and thermally and/or catalyticallycracked distillates. Preferred diesel fuels have a cetane number of atleast 40, preferably above 45, and more preferably above 50.

The diesel fuel can have such cetane numbers prior to the addition ofany cetane improver. The cetane number of the fuel can be raised by theaddition of a cetane improver.

When the fuel is gasoline, it can be derived from straight-chainnaphtha, polymer gasoline, natural gasoline, catalytically cracked orthermally cracked hydrocarbons, catalytically reformed stocks, etc. Itwill be understood by one skilled in the art that gasoline fuelstypically boil in the range of about 80°-450° F. and can containstraight chain or branched chain paraffins, cycloparaffins, olefins,aromatic hydrocarbons, and any mixture of these.

Generally, the composition of the fuel is not critical and anyconventional motor fuel base can be employed in the practice of thisinvention.

The proper concentration of the foregoing esterified polyalkene/UARcopolymer reaction products of the present invention that are necessaryto achieve the desired friction modification in fuel compositions isdependent upon a variety of factors including, for example, the type offuel used, the presence of other additives, etc. Generally, however, therange of esterified copolymer additive concentration in the base fuel isfrom about 10 to about 10,000 parts per million and preferably fromabout 30 to about 5000 parts per million of the additive per part ofbase fuel. If other friction modifiers are present, a lesser amount ofthe esterified copolymer additive may be used.

The additives described herein may also be formulated as a fuelconcentrate, using an inert stable oleophilic organic solvent boiling inthe range of about 150 EF. to about 400 EF. An aliphatic or an aromatichydrocarbon solvent is preferred, e.g., solvents such as benzene,toluene, xylene or higher-boiling aromatics or aromatic thinners.Aliphatic alcohols of about 3 to 8 carbon atoms, e.g., isopropanol,isobutylcarbinol, n-butanol and the like, in combination withhydrocarbon solvents are also suitable for use with the fuel additive.In the fuel concentrate, the amount of the additive will be ordinarilybe about 5 or more wt. % and generally not exceed about 70 wt. %,preferably from about 5 wt. % to about 50 wt. % and more preferably fromabout 10 wt. % to about 25 wt. %.

Cold Flow Improver

It is also contemplated that the foregoing esterified PIB/UAR copolymerand post-treated esterified PIB/UAR copolymers of the present inventionare useful as cold flow improvers in diesel fuels.

The following non-limiting examples are illustrative of the invention.

EXAMPLE 1 Preparation of PIB/MA Copolymer

To a 20 L 3 neck glass round bottom reactor equipped with a mechanicalstirrer, thermocouple, temperature controller, heat mantle, Claisenadapter, Dean-Stark trap, reflux condenser, nitrogen inlet, and septumwas added 4025 g (7.32 mol) of 550 MW polyisobutylene (available fromBASF) having greater than 60% of the methyl vinylidene isomer with 3051g of Exxon 100 solvent (a C₉ aromatic solvent). The mixture was stirredunder nitrogen, and heated to 130° C.; and 15 ml was collected in thetrap. Next, 681.5 g (6.95 mol) of maleic anhydride was added in two170.4 g aliquots and one 340.8 g aliquot at approximately 60 minuteintervals. 67 ml (0.366 mol) di-t-butyl peroxide was added in five 13.4ml aliquots at approximately 30 minute intervals coincident with themaleic anhydride addition. The reactants were stirred at 130° C. for anadditional 16 hours. The solvent and unreacted maleic anhydride werethen removed, en vacuo, at 200° C. to yield a yellow oil having a sapnumber of 105.7 mg KOH/g.

EXAMPLE 2 Preparation of Esterified PIB/MA Copolymer

To a 2 L 3 neck glass round bottom reactor flask equipped with amechanical stirrer, thermocouple, temperature controller, heat mantle,Dean-Stark trap, reflux condenser, and nitrogen inlet was added 535 g ofthe maleic anhydride/polybutene copolymer of example 1 and 59.19 g(0.435 mol, 0.88 equivalents) of pentaerythritol. The reactants werestirred, under a gentle sweep of nitrogen, at 190° C. for about 3.5hours to yield 567.5 g of a viscous yellow oil that contained unreactedpentaerythritol. The crude product was diluted with 358.7 g of Exxon 150neutral oil (a group I basestock) and was pressure filtered throughCelite superflow filter aid to yield a yellow oil.

EXAMPLE 3 Preparation of Esterified PIB/MA Copolymer

To a 20 L 3 neck glass round bottom reactor equipped with a mechanicalstirrer, thermocouple, temperature controller, heat mantle, Claisenadapter, Dean-Stark trap, reflux condenser, nitrogen inlet, and septumwas added 4027 g (7.32 mol) of 550 MW polyisobutylene (available fromBASF) having greater than 60% of the methyl vinylidene isomer, 686.1 g(7.00 mol) of maleic anhydride, and 2884 g of Exxon 100 solvent (a C₉aromatic solvent). The reactants were stirred, under nitrogen, andheated to 130° C. Dicumyl peroxide 94.2 g (0.348 mol) was added,dissolved in Exxon 100 solvent, in four 60 ml aliquots and one 200 mlaliquot at approximately 30 minute intervals. The reactants were stirredat 130° C. for an additional 16 hours. Solvent and unreacted maleicanhydride were removed, en vacuo, at 200° C. Then, 638.8 g (4.69 mol) ofpentaerythritol was added and the mixture was stirred, heated at 190°C., and a gentle sweep of nitrogen was passed through the reactor forabout 4 hours. The product was diluted with 2681 g of Exxon 150N oil andfiltered through Celite superflow filter aid to yield an amber oil.

EXAMPLE 4 Post Treatment of Esterified Copolymer

To a 2 L three neck glass round bottom flask equipped with a mechanicalstirrer, thermocouple, temperature controller, heat mantle, Dean-Starktrap, reflux condenser, and nitrogen inlet was added 169.7 g of theproduct from example 2, 16.97 g (0.275 mol) of boric acid, and 16.5 g ofdeionized water. The reactants were stirred, under a gentle nitrogensweep, and heated at 95° C. for about 3.5 hours, then at 145° C. forabout 1.5 hours, and finally at 170° C. for about 1 hour followed byvacuum for about 5 minutes. The product was pressure filtered throughcelite superflow filter aid to yield a yellow oil that contained 0.65%boron by weight.

EXAMPLE 5 Frictional Properties in Automatic Transmission Fluid

A baseline automatic transmission fluid was formed containing aconventional base oil, together with conventional additives, including2.5 mM/kg of an synthetic overbased calcium sulfonate on a calciumbasis, 0.4% of an amine anti-oxidant, 0.25% of a phenolic anti-oxidant,0.2% of an alkyl phosphate, 1% of a fatty acid, 2% of an amide frictionmodifier, and other conventional additives selected from a foaminhibitor, corrosion inhibitor and dispersant. The reaction product ofExample 2 was formulated into this baseline fluid at 4.5 weight percent.

COMPARATIVE EXAMPLE A

Frictional Properties in Automatic Transmission Fluid

A baseline automatic transmission fluid was formed containing the sameadditives, base oil and treat rate, as in Example 5. A commerciallyavailable polyisobutenyl succinate ester, prepared by reacting apolyisobutenyl succinic anhydride monomer with pentaerythritol, wasformulated into this baseline fluid at 4.5 weight percent.

SAE #2 Friction TEST

The automatic transmission fluids of Example 5 and Comparative Example Awere evaluated, under identical conditions, in an SAE number 2 testsystem according to JASO M348-2002, described in Watanabe, N. et al “Therequirements for the Latest ATF and Problems of Commercially AvailableATF” which was presented at SAE Fuels and Lubes Asia Conference—February2002. This test was used to evaluate the frictional properties ofautomatic transmission fluids. Results are measured by frictioncoefficients and are related to the torque capacity of the test fluidwhere a higher friction coefficient corresponds to a desirable, hightorque capacity. The results of this evaluation are outlined in FIG. 1where the higher line corresponds to the automatic transmission fluid ofExample 5, and the lower line to the automatic transmission fluid ofComparative Example A. These results show the superior frictionalproperties of the automatic transmission fluid of Example 5 as comparedto the automatic transmission fluid of Comparative Example A. Inaddition, Comparative Example A provided unstable friction whichresulted in the early termination of the test.

EXAMPLE 6 Diesel Fuel Economy

A diesel fuel composition was prepared by adding 210 PTB of theesterified PIB/MA copolymer reaction product of Example 2 to a baselinediesel fuel.

COMPARATIVE EXAMPLE B

The baseline diesel fuel of Example 6 containing no esterified PIB/MAcopolymer reaction product was employed as a comparative example in thediesel fuel economy test below.

Diesel Fuel Economy Test

The diesel fuel composition of Example 6 was compared to the baselinediesel fuel of Comparative Example B in a diesel engine fuel economytest. A 1.9 liter 4 cylinder Volkswagen TDI diesel engine wasconditioned by motoring at 2200 rpm under 75 lb-ft load for 16 hours.The diesel fuel composition of Example 6 and baseline diesel fuel ofComparative Example B were then evaluated in the following testsequence. The engine was motored under 25 lb-ft load with the oil sumptemperature controlled at 150, 200, 250, 250, 200, and 150° F. in stagesof 2 hours each for a total running time of 12 hours; fuel consumptionwas measured by conventional methods. The baseline diesel fuel ofComparative Example B was tested, followed by the diesel fuelcomposition of Example 6. The diesel fuel composition of Example 6containing the esterified PIB/MA copolymer reaction product of Example 2resulted in a 2% fuel economy improvement as calculated by a comparisonof the fuel consumption from the Example 6 test run to the fuelconsumption from the Comparative Example B test run.

It will be understood that various modifications may be made to theembodiments disclosed herein. Therefore the above description should notbe construed as limiting, but merely as exemplifications of preferredembodiments. For example, the functions described above and implementedas the best mode for operating the present invention are forillustration purposes only. Other arrangements and methods may beimplemented by those skilled in the art without departing from the scopeand spirit of this invention. Moreover, those skilled in the art willenvision other modifications within the scope and spirit of the claimsappended hereto.

1-42. (canceled)
 43. A product prepared by the process comprisingreacting at least one esterified polyalkene/unsaturated acidic reagentcopolymer which is the reaction product of a polyol and a copolymer ofthe general formula:

wherein X and X′ in each repeating unit of the copolymer areindependently selected from the group consisting of —OH: —O—R₃ whereinR₃ is a lower alkyl of 1 to 6 carbon atoms; or taken together are —O— toform a succinic anhydride group: n is a whole integer from 1 to 3; R₁ isa lower alkyl of 1 to 6 carbon atoms: R₂ is a polyalkyl group havingabout 9 to about 200 carbon atoms: m is a whole integer of from 1 to 3:x is a number greater than 1 up to 20: Int. is at least one initiatingradical: and Ter. is at least one terminating group: and wherein thecopolymer has a succinic ratio of about 1 under reactive conditions withone or more cyclic carbonates.
 44. The product of claim 43, wherein thecyclic carbonate is ethylene carbonate.
 45. A product prepared by theprocess comprising reacting at least one esterifiedpolyalkene/unsaturated acidic reagent copolymer which is the reactionproduct of a polyol and a copolymer of the general formula:

wherein X and X′ in each repeating unit of the copolymer areindependently selected from the group consisting of —OH; —O—R₃ whereinR₃ is a lower alkyl of 1 to 6 carbon atoms; or taken together are —O— toform a succinic anhydride group; n is a whole integer from 1 to 3; R₁ isa lower alkyl of 1 to 6 carbon atoms; R₂ is a polyalkyl group havingabout 9 to about 200 carbon atoms; m is a whole integer of from 1 to 3;x is a number greater than 1 up to 20; Int. is at least one initiatingradical; and Ter. is at least one terminating group; and wherein thecopolymer has a succinic ratio of about 1 under reactive conditions withone or more of a boron compound selected from the group consisting ofboron oxide, boron halide, boric acid, and esters of boric acid.
 46. Theproduct of claim 45, wherein the boron compound is boric acid. 47-49.(canceled)
 50. A lubricating oil concentrate comprising from about 10wt. % to about 90 wt. % of the product of claim 43 and from about 90 wt.% to about 10 wt. % of an oil of lubricating viscosity.
 51. Alubricating oil concentrate comprising from about 10 wt. % to about 90wt. % of the product of claim 45 and from about 90 wt. % to about 10 wt.% of an oil of lubricating viscosity. 52-54. (canceled)
 55. Alubricating oil composition comprising a major amount of an oil oflubricating viscosity and a friction modifying effective amount of theesterified copolymer of claim
 43. 56. A lubricating oil compositioncomprising a major amount of an oil of lubricating viscosity and afriction modifying effective amount of the product of claim
 45. 57-64.(canceled)
 65. A fuel concentrate comprising an inert stable oleophilicorganic solvent boiling in the range of about 150° F. to about 400° F.and about 5 to about 70 wt. % of the product of claim
 43. 66-68.(canceled)
 69. A fuel composition comprising a major amount of ahydrocarbon fuel and a minor friction modifying effective amount of theproduct of claim
 43. 70-72. (canceled)
 73. The fuel composition of claim69, wherein the hydrocarbon fuel is a diesel fuel. 74-79. (canceled) 80.The product of claim 43, wherein R₁ is methyl and R₂ is a polyisobutylgroup.
 81. The product of claim 43, wherein R₂ is a polyisobutyl grouphaving a number average molecular weight of about 210 to about
 1400. 82.The product of claim 43, wherein the polyalkyl group is derived from apolyalkylene having at least 20 percent of an alkylvinylidene isomer.83. The product of claim 43, wherein the polyol is pentaerythritol. 84.The product of claim 43, wherein the reaction product is from about 40to about 70% esterified.
 85. The product of claim 45, wherein R₁ ismethyl and R₂ is a polyisobutyl group.
 86. The product of claim 45,wherein R₂ is a polyisobutyl group having a number average molecularweight of about 210 to about
 1400. 87. The product of claim 45, whereinthe polyalkyl group is derived from a polyalkylene having at least 20percent of an alkylvinylidene isomer.
 88. The product of claim 45,wherein the polyol is pentaerythritol.
 89. The product of claim 45,wherein the reaction product is from about 40 to about 70% esterified.